The Assignee of the instant application, Paper Machinery Corporation of Milwaukee, Wis. U.S.A. is the manufacturer of paper cup making machines used to make a variety of cups and containers. A typical cup machine for making paper cups, for instance, includes a turret having a plurality of mandrels about which the containers are formed. The turret sequentially rotates the mandrels into cooperation with a variety of work stations where numerous cup forming procedures occur.
In an exemplary procedure, a circular bottom blank is cut out at one work station and attached to the end of a mandrel by a vacuum applied through the mandrel. During this procedure, the outside lip of the bottom blank is folded downwardly. At a subsequent work station, a side wall blank is wrapped around a mandrel. The side wall blank is heated and sealed using a seam clamp along an overlapped side seam which runs generally longitudinally along the side of the cup. Typically, a paperboard or solid plastic sheet is coated with a thermoplastic such as polyethylene, so the bottom and side wall blanks may be heated and sealed together. In some applications, the side wall blank includes a flap extending beyond the lip of the side wall blank, and this flap is bent over the lip. At a bottom finishing station, the flap is pressed against the lip from an inside recessed area of the bottom of the cup. By heating the polyethylene and firmly pressing the side wall flap and the bottom blank lip together, a bottom seal is formed and the cup is provided with a sturdy bottom region having a recessed area. There may also be other work stations where various other additional cup forming procedures are carried out. For example, one station may be used to provide a curl at the top or rim of the cup to provide a more functional drinking container and a better appearance.
Cups and containers produced according to the procedure outlined above typically do not have the ability to keep beverages and food products stored therein warm and, at the same time, protect the hand from becoming uncomfortable from holding a hot liquid or material. Similarly, such cups and containers do not have the ability to insulate a cold beverage or products and protect the exterior of the cold container from moisture condensation that may pool on the bottom of the container.
Many cups and containers have been produced with sleeves, overwraps or laminates to provide a thermally insulated double walled cup or container with an air gap between inner and outer walls to create hand-hold protection in addition to heat and cold retention in the beverage or food product contained therein.
In development of the present disclosure, the inventors have discovered that the air gap created between the inner and outer walls of the container is not always uniform therebetween. For example, it has been found that when applying an overwrap around a base cup or container, the air gap is substantially eliminated in the seam area formed by the overlapping opposite edges of the overwrap. This is due to the mechanical clamping which normally occurs along the length of the overwrap side seam. Such anomaly leads to the formation of a zone along the overwrap seam which makes the container or cup uncomfortable or inconvenient to hold relative to the remainder of the holding surface of the container or cup.
Accordingly, there remains a need to provide a double walled insulated container which overcomes the short comings of previous designs, and creates an overwrap container with a uniform air gap between the inner and outer walls of the container so as to ensure comfort of the holder of the overwrap container around its entire outer periphery. In addition, it is desirable to provide a method of and an apparatus for forming such an overwrap container.